William ate 5 slices of pizza. Ishaan ate 4 slices. If William ate $\dfrac{5}{13}$ of the pizza, what fraction of the pizza was eaten?
Explanation: If 5 slices represent $\dfrac{5}{13}$ of the pizza, there must have been a total of 13 slices. $\text{fraction of pizza eaten} = \dfrac{\text{number of slices eaten}}{\text{number of slices total}}$ They ate ${9}$ out of $13$ slices. They ate $\dfrac{9}{13}$ of the pizza.